title: Deficiency of the purine metabolic gene HPRT dysregulates microRNA-17 family cluster and guanine-based cellular functions: a role for EPAC in Lesch-Nyhan syndrome.
abstract: Lesch-Nyhan syndrome (LNS) is a neurodevelopmental disorder caused by mutations in the gene encoding the purine metabolic enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT). A series of motor, cognitive and neurobehavioral anomalies characterize this disease phenotype, which is still poorly understood. The clinical manifestations of this syndrome are believed to be the consequences of deficiencies in neurodevelopmental pathways that lead to disordered brain function. We have used microRNA array and gene ontology analysis to evaluate the gene expression of differentiating HPRT-deficient human neuron-like cell lines. We set out to identify dysregulated genes implicated in purine-based cellular functions. Our approach was based on the premise that HPRT deficiency affects preeminently the expression and the function of purine-based molecular complexes, such as guanine nucleotide exchange factors (GEFs) and small GTPases. We found that several microRNAs from the miR-17 family cluster and genes encoding GEF are dysregulated in HPRT deficiency. Most notably, our data show that the expression of the exchange protein activated by cAMP (EPAC) is blunted in HPRT-deficient human neuron-like cell lines and fibroblast cells from LNS patients, and is altered in the cortex, striatum and midbrain of HPRT knockout mouse. We also show a marked impairment in the activation of small GTPase RAP1 in the HPRT-deficient cells, as well as differences in cytoskeleton dynamics that lead to increased motility for HPRT-deficient neuron-like cell lines relative to control. We propose that the alterations in EPAC/RAP1 signaling and cell migration in HPRT deficiency are crucial for neuro-developmental events that may contribute to the neurological dysfunctions in LNS.
authors.affiliation: Department of Pediatrics, Division of Genetics/Rady Children's Hospital and.
authors.forename: Ghiabe-Henri
authors.initials: GH
authors.lastname: Guibinga
authors.forename: Fiona
authors.initials: F
authors.lastname: Murray
authors.forename: Nikki
authors.initials: N
authors.lastname: Barron
authors.forename: William
authors.initials: W
authors.lastname: Pandori
authors.forename: Gorjan
authors.initials: G
authors.lastname: Hrustanovic
mesh_terms: D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D002540:Cerebral Cortex / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D063990:Gene Ontology; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000172:deficiency / Q000235:genetics; D007926:Lesch-Nyhan Syndrome / Q000201:enzymology / Q000235:genetics*; D008297:Male; D008636:Mesencephalon / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D020411:Oligonucleotide Array Sequence Analysis; D015398:Signal Transduction; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C482601:Epac protein, mouse; D020662:Guanine Nucleotide Exchange Factors; C524941:MIRN17 microRNA, human; D035683:MicroRNAs; C116122:RAPGEF3 protein, human; D007041:Hypoxanthine Phosphoribosyltransferase; D020827:rap1 GTP-Binding Proteins